The invention relates generally to a local wireless communication system and, more particularly, to a wireless communication system using radio frequencies for transmitting and receiving voice and data signal with an internal network with multiple internal communication paths, and multiple external communication paths for linking the internal network to an external communication networks.
Wireless communication systems continue to grow, particularly in the areas of cellular and digital telephony and in paging systems. Wireless systems are especially popular in remote areas of the world that have limited wired service because of the cost and difficulty of building a wired infrastructure.
Current traditional wireless communication systems such as cellular telephones use radio communication between a plurality of subscriber units within the synchronous wireless system and between subscriber units and the Public Switched Telephone Network (PSTN) for calls that are outside of the wireless system. Most of these systems are characterized by wireless mobile telephone units communicating synchronously with base stations that are connected to centralized mobile switching centers (MSC), which are in turn connected to the PSTN. The centralized MSC performs a number of functions, including routing wireless mobile units calls to other mobile units and wired (land-line) users and routing land-line calls to mobile units. The MSC accomplishes this by being connected to base stations for accessing mobile users and by being connected to the PSTN for accessing users outside the wireless system, be they other wireless users in other wireless systems or land-line users. Therefore the MSC functions, as its name implies, as a switching and routing center that controls the overall operation of the systems. This results in a centralized calling system with the MSC being involved in routing all the calls to and from the wireless system. This centralization allows the MSC to be the primary collection point for compiling billing information for its wireless mobile units. The centralized MSC also creates a need for expensive infrastructure equipment. As more mobile telephone units are added to the system, the MSC must in turn expand to be able to handle the additional volumes of phone calls, connections and the associated billing services. In addition, since the base stations provide the connection to the mobile units, a large increase in the number of mobile units within an area covered by the base station can overload the base station, thus requiring more base stations and/or enhancing the capabilities of the base stations.
Others systems use point-to-point radio communication where mobile units may communicate with other mobile units in the local area. They send origin and destination address information and make use of squelching circuits to direct the wireless transmission to the correct destination address. Most of these systems do not appear to provide a connection to a PSTN to send and receive calls outside the wireless network. This type of system is decentralized, but because of the decentralization, collecting accurate billing information may be a problem.
However, most wireless systems still require a synchronous centralized system where a wireless base station (fixed or mobile) operates through a centralized switching center for communication within the synchronous wireless network and for communication outside the wireless network, for example to a PSTN. In many cellular and digital wireless systems, base station controllers cover a geographical area and are connected to a mobile services switching center. When a cellular or digital mobile unit places a call, the call is routed synchronously to the base station controller serving the mobile unit""s geographical area and the base station controller synchronously connects the unit to the centralized switching center which in turn routes the call to its appropriate destination. As more wireless units come online in a geographical area, base station controllers and switching centers must be added or upgraded.
Another form of wireless system is called a local multipoint distribution service (LDMS). In an LMDS system, a local area or cell that is approximately 4 km in diameter contains fixed base stations, geographically distributed throughout the local area. One or more antennas within the local area receive calls from the fixed base stations and relay the calls to other fixed base stations. In order for the system to work, the fixed base stations must be within the line-of-sight path of at least one of the antenna units. The LDMS does not provide for mobile stations. Calls can only be routed within the local area and not to an external network. The system is essentially a centralized system within a local area. If one station is not within the line of sight of the antenna, it is effectively cut off from communication.
Therefore there is a need for decentralized wireless communication system for voice and data communication that allows for a flexibility of communication paths, provides local communication as well as optional links to external networks, such as public switch telephone networks, satellites and radio emergency networks, does not require a centralized switching center, provides for secure operation, allows for control the operational state of the internal network, provides for emergency notification and provides a way to collect revenue from the system.
The present invention is directed to a device and method of use that satisfies these needs. It provides a decentralized asynchronous wireless communication system for voice and data communication that allows for a flexibility of communication paths, provides local communication as well as optional links to external networks, such as public switch telephone networks, satellites and radio emergency networks, does not require a synchronous centralized switching center, provides for secure operation, allows for control the operational state of the internal network, provides for emergency notification and provides a way to collect revenue from the system.
The present invention provides a wireless communication system using radio frequencies for asynchronously transmitting and receiving voice and data signals within an internal network with multiple internal communication paths. It also provides for external communication paths for linking the internal network to external communication networks and is suited to operate in isolated remote locations.
The system provides wireless telecommunication services that are similar, from a user""s perspective, to the services provided by other technologies, such as cellular and PCS. The system consists of three primary elements: handsets carried by mobile users, signal extenders for relaying handset signals, and network extenders for interconnecting signals. The signal extenders and network extenders comprise the infrastructure equipment that are located at antenna tower sites. Handsets are assigned standard telephone numbers and are capable of placing and accepting calls with telephones in the public-switched system through the network extenders. Calls that are placed between handsets contained within the asynchronous internal network do not require routing through a PSTN. This is in contrast to synchronous cellular/PCS systems that rely on a PSTN backbone. Besides handling regular voice and data, the system also supports a wide variety of telephone features such as caller ID, call waiting, and text messaging.
The system is particularly suitable for operation in rural areas where population density is low and wireless coverage is either not available or not adequately serviced. The system is suitable for operation in the United States using the Broadband PCS spectrum (1850-1975 MHz) that is licensed by the Federal Communications Commission (FCC). The handset incorporates a modular dual-mode capability to extend the wireless service area with a potential variety of standard wireless formats and bands, such as AMPS, D-AMPS, IS-95, IS-136, and GSM1900. This is an important feature because widespread deployment of a new wireless service takes appreciable time, and there are many other wireless standards from which to chose since these new customers may also venture into standard PCS or cellular markets. Besides the US rural market, other applications for present invention include emerging nations, especially those that presently have limited or no telephone service, and those communities or groups that require a standalone wireless communication network that can be quickly and cost-effectively deployed.
A fourth element, known as a Communications Docking bay (ComDoc) provides additional connectivity to the PSTN, if required. The ComDoc is a fixed-base wireless set capable of asynchronously sending and receiving system calls and/or providing connection with a PSTN. This device reduces the load on the network extender PSTN interface and provides a redundant path to a PSTN. The ComDoc also serves as a battery charging station for handsets.
A method having features of the present invention comprises establishing a local communication path for transmitting and receiving signals between local handsets within a same microcell via a signal extender, establishing an extended communication path for transmitting and receiving signals between extended handsets within different microcells positioned within a same macrocell via signal extenders and a network extender, and establishing a distant communication path for transmitting and receiving signals between distant handsets within different microcells positioned within different macrocells via signal extenders and network extenders. The step of establishing a local communication path may comprise transmitting signals from the local handsets to the signal extender, transmitting signals from the signal extender to the local handsets, and receiving signals from the signal extender by the local handsets. The step of establishing an extended communication path may comprise transmitting signals from the extended handsets to the signal extenders, transmitting signals from the signal extenders to the network extender, transmitting signals from the network extender to the signal extenders, transmitting signals from the signal extenders to the extended headsets, and receiving signals from the signal extender by the extended handsets. The step of establishing a distant communication path may comprise transmitting signals from the distant handsets to the signal extenders, transmitting signals from the signal extenders to the network extenders, transmitting signals between the network extenders, transmitting signals from the network extenders to the signal extenders, transmitting signals from the signal extenders to the distant headsets, and receiving signals from the signal extenders by the distant handsets. The step of transmitting signals between the network extenders may be selected from the group consisting of transmitting signals over a Public Switch Telephone Network, transmitting signals over a fiber optic communication link, transmitting signals over a coaxial cable, transmitting signals over a public TCP/IP network, and transmitting signals over a satellite communication link. Half of the signals received by a signal extender in a microcell may be transmitted by handsets in the microcell in a low radio frequency band and half of the signals received by the signal extender in a macrocell may be transmitted by a network extender in the macrocell in a low radio frequency band. Half of the signals transmitted by a signal extender in a microcell may be received by the handsets in the microcell in a high radio frequency band and half of the signals transmitted by the signal extender in a macrocell may be received a network extender in the macrocell in a high radio frequency band. Transmitting signals between a first handset and a second handset may be conducted asynchronously with transmitting signals between other handsets. The step of establishing a local communication path may comprise using two fixed frequencies in a sub-band spectrum for establishing a local voice data channel. The step of establishing an extended communication path may comprise using four fixed frequencies in a sub-band spectrum for establishing an extended voice data channel.
In an alternate embodiment of the invention, a method of operating a wireless communication system for transmitting and receiving voice and data signals comprises establishing a local communication path for transmitting and receiving signals between local handsets within a same microcell, comprising transmitting signals from the local handsets to a signal extender, transmitting signals from the signal extender to the local handsets, and receiving signals from the signal extender by the local handsets, establishing an extended communication path for transmitting and receiving signals between extended handsets within different microcells positioned within a same macrocell comprising transmitting signals from extended handsets to signal extenders, transmitting signals from the signal extenders to a network extender, transmitting signals from the network extender to the signal extenders, transmitting signals from the signal extenders to extended headsets, and receiving signals from the signal extender by the extended handsets, establishing a distant communication path for transmitting and receiving signals between distant handsets within different microcells positioned within different macrocells comprising transmitting signals from distant handsets to signal extenders, transmitting signals from the signal extenders to network extenders, transmitting signals between the network extenders, transmitting signals from the network extenders to the signal extenders, transmitting signals from the signal extenders to the distant headsets, and receiving signals from the signal extender by the distant handsets. The step of transmitting signals between the network extenders may be selected from the group consisting of transmitting signals over a Public Switch Telephone Network, transmitting signals over a fiber optic communication link, transmitting signals over a coaxial cable, transmitting signals over a public TCP/IP network, and transmitting signals over a satellite communication link. The steps of transmitting signals from the handsets to a the signal extenders may be in a low radio frequency band and transmitting signals from the signal extenders to the handsets may be in a high radio frequency band, transmitting signals from the signal extenders to the network extenders may be in a high radio frequency band and transmitting signals from the network extenders to the signal extenders may be in the low radio frequency band, and transmitting signals between the network extenders may on a high data rate system backbone. Half of the signals received by a signal extender in a microcell may be transmitted by handsets in the microcell in a low radio frequency band and half of the signals received by the signal extender in a macrocell may be transmitted by a network extender in the macrocell in a low radio frequency band. Half of the signals transmitted by a signal extender in a microcell may be received by the handsets in the microcell in a high radio frequency band and half of the signals transmitted by the signal extender in a macrocell may be received a network extender in the macrocell in a high radio frequency band. Transmitting signals between a first handset and a second handset may be conducted asynchronously with transmitting signals between other handsets. The steps of transmitting signals may comprise using Frequency Division Multiple Access techniques for determining sub-bands in the high and low radio frequency bands. The steps of transmitting signals may comprise using Gaussian Minimum Shift Keying modulation for producing a radio frequency waveform. Transmitting signals from handsets and transmitting signals to handsets may comprise a primary mode and a secondary mode of operation. The primary mode of operation may comprise a DW wireless frequency protocol. The secondary mode of operation is selected from the group of wireless protocols consisting of AMPS, D-AMPS, IS-95, IS-136, and GSM1900. The method may further comprise controlling an operational state of the wireless communication system by transmitting an operational state command to a network extender. The step of establishing a local communication path may comprise using two fixed frequencies in a sub-band spectrum for establishing a local voice data channel. The step of establishing an extended communication path may comprise using four fixed frequencies in a sub-band spectrum for establishing an extended voice data channel. The transmitting signals may comprise digitizing, buffering and encoding voice frames and transmitting the voice frames in packets at a date rate that is at least twice that required for real-time decoding, whereby transmitting time requires less than half of real time, and the receiving signals may comprise receiving and decoding the voice frame packets at a data rate that is equal to that required for real-time decoding, whereby receiving time requires less than half of real-time. The method may further comprise transmitting and receiving information over a reference channel for providing a handset with time and date information, microcell and macrocell identification code, attention codes, and broadcast text messages. The method may further comprise transmitting and receiving information over a call initiation channel for handling handset initial registration, handset periodic registration, handset authorization and short id assignment, call requests, call frequency assignment, call progress prior to voice and data channel use, and acknowledgement. The method may for comprise transmitting and receiving information over a call maintenance channel for call completion, call request, 911 position report, call handoff frequency, call waiting notification, voice message notification, text message notification, and acknowledgement.
In another alternate embodiment of the present invention, a wireless communication system for transmitting and receiving voice and data signals comprises means for establishing a local communication path for transmitting and receiving signals between local handsets within a same microcell via a signal extender, means for establishing an extended communication path for transmitting and receiving signals between extended handsets within different microcells positioned within a same macrocell via signal extenders and a network extender, and means for establishing a distant communication path for transmitting and receiving signals between distant handsets within different microcells positioned within different macrocells via signal extenders and network extenders. The means for establishing a local communication path for transmitting and receiving signals between local handsets within a same microcell via a signal extender may comprise a first local handset for encoding voice and data frame packets and transmitting these packets as radio frequency signals in a low radio frequency band, a signal extender for receiving, amplifying, and shifting a frequency of local handset signals in the low radio frequency band to a high radio frequency band and transmitting the high radio frequency band signals, a second local handset for receiving signals in the high radio frequency band from the signal extender and decoding the received signals into a voice and data frame packet, the second local handset for encoding voice and data frame packets and transmitting these packets as radio frequency signals in a low radio frequency band, and the first local handset for receiving signals in the high radio frequency band from the signal extender and decoding the received signals into a voice and data frame packet. The means for establishing an extended communication path for transmitting and receiving signals between extended handsets within different microcells positioned within a same macrocell via signal extenders and a network extender may comprise a first extended handset for encoding voice and data frame packets and transmitting these packets as radio frequency signals in a low frequency band, a first signal extender for receiving, amplifying, and shifting a frequency of the first extended handset signals in the low radio frequency band to a high radio frequency band and transmitting the high radio frequency band signals from the first signal extender to the network extender, the network extender for receiving, amplifying, and shifting a frequency of signal extender signals in the high radio frequency band to a low radio frequency band and transmitting the low radio frequency band signals from the network extender to selected signal extenders, the second signal extender for receiving, amplifying, and shifting a frequency of the network extender signals in the low frequency band to a high radio frequency band and transmitting the high radio frequency band signals, a second extended handset for receiving the second signal extender signals in the high radio frequency band and decoding the received signals into a voice and data frame packet, the second extended handset for encoding voice and data frame packets and transmitting these packets as radio frequency signals in a low frequency band, the second signal extender for receiving, amplifying, and shifting a frequency of the second extended handset signals in the low radio frequency band to a high radio frequency band and transmitting the high radio frequency band signals from the second signal extender to the network extender, the first signal extender for receiving, amplifying, and shifting a frequency of the network extender signals in the low frequency band to a high radio frequency band and transmitting the high radio frequency band signals, and the first extended handset for receiving the first signal extender signals in the high radio frequency band and decoding the received signals into a voice and data frame packet. The means for establishing a distant communication path for transmitting and receiving signals between distant handsets within different microcells positioned within different macrocells via signal extenders and network extenders may further comprise a first network extender for receiving, amplifying the first signal extender signals and transmitting the first signal extender signals to a second network extender over a dedicated communication link, and the second network extender for receiving and shifting a frequency of first signal extender signals in the high radio frequency band to a low radio frequency band and transmitting the low radio frequency band signals from the second network extender to the second signal extender. A microcell may comprise a geographical area containing one or more handsets carried by mobile users and a signal extender and a macrocell may comprise a geographical area containing between one and twenty-one microcells, and a network extender. The signal extender may amplify and translate the frequency of wireless signals for relay between handsets and between handsets and a network extender. The network extender is a central hub and switch for establishing calls, managing voice, data, and signaling channels, and interconnecting calls within the system and to external networks. The dedicated communication link may be selected from the group consisting of a Public Switch Telephone Network, a fiber optic communication link, a coaxial cable, a public TCP/IP network, and a satellite communication link. The handsets may comprise a processor for controlling handset operation comprising a digital signal processor, a controller, permanent memory, non-volatile memory, and volatile memory, a user interface comprising a display, a keypad, ringer devices, microphone and speaker, a vocoder connected to a microphone and speaker interface, a power manager and power source, an external data interface, a 911 position locator, a primary mode transceiver having a transmitter and two receivers connected to an omni-directional antenna for use with a DW protocol, and a secondary mode transceiver for providing service using a standard protocol. The handsets may transmit voice and data packets half of the time and receive voice and data packets half of the time when in use. The signal extenders may comprise an omni-directional antenna connected to an omni duplexer for establishing communication paths with handsets, a directional antenna connected to a directional duplexer for establishing communication paths with network extenders, a controller for controlling operation of the signal extender, an uplink translator for shifting a frequency of signals received from handsets from a low radio frequency band to a high radio frequency band for transmission to network extenders, a downlink translator for shifting a frequency of signals received from network extenders from a low radio frequency band to a high radio frequency band for transmission to handsets, a local translator for shifting a frequency of signals received from handsets from a low radio frequency band to a high radio frequency band for transmission to other handsets, and power amplifiers, low noise amplifiers, a control transceiver and an uninterruptible power supply. The network extenders may comprise directional antennas connected to microcell transceiver banks for establishing communication paths with signal extenders Within microcells, microcell servers associated with the microcell transceiver banks for performing control functions associated with each microcell, a global positioning system reference source for stabilizing local oscillators, a central switch for connecting to other macrocells and external communication networks, a central processor for coordinating call activity within the network extender, an Internet interface, public switched telephone network interface and interfaces to other network extenders, and an uninterruptible power supply.